Meet Ryan Phillippe and Alexis Knapp's Daughter Kailani!

On Monday, So Undercover actress AlexisKnapp, 21, shared an adorable photo of her 3-month-old daughter with ex-boyfriend RyanPhillippe, 37. "I do declare you to be the prettiest lil girl in the whole wide world," Knapp wrote on her WhoSay page.

Knapp announced her pregnancy at an industry event in mid-February -- five months after she and the Lincoln Lawyer star officially ended their on-and-off relationships. (Phillippe was dating AmandaSeyfried at the time; they have since split.)

Though Phillippe has not confirmed his paternity -- as of July 25, a source told Us Weekly he had not taken a DNA test -- he's found support from his ex-wife ReeseWitherspoon, 35, with whom he has two children: Ava, 11, and Deacon, 7.